Your truly is no stranger to sensor for the purpose of temperature data acquisition. The matter of fact, expensive sensor does matter http://shin-ajaran.blogspot.sg/2013/07/expensive-sensor-does-matter-ds18b20.html. Obviously, the weapon of choice in this application will be the trusty DS18B20 temperature probe, or it's variant. Setting up DS18B20 can be slightly tedious as compared to LM35, but it is well worth the effort. As far as my DIY sous vide setup is concerned, DS18B20 temperature sensor served it's purpose.

If you can't wait to make it yourself and want to jump straight into the visualization of the temperature in the office from the internet, follow this URL https://thingspeak.com/channels/22051

Wiring:
please refer to the previous posts mentioned earlier on hooking up the ESP8266 with Arduino Mega, and DS18B20 temperature sensor.

Once every partss are wired accordingly and dandy, the final outcome should look somewhat similar to the following.

API:

Go to the thingspeak website to register for an account. it is FREE!!!!
Once registration is done, navigate to the following to acquire the API key.
This API key will allow ESP8266 and Arduino Mega to send data to thingspeak server.

program arduino mega with the code that is available at the footer.
then observe from the serial monitor whether data has been sent successfully. On the thingspeak channel of yours, a simple graph is available to visualize the data received via IoT.

there are several cool features on thingspeak, such as public view and private view of streaming data; data can be downloaded in CSV for later manipulations.

the following is the said temperature sensor data from the office, streamed to thingspeak using ESP8266 and Arduino Mega since 31dec14.

can you spot the trend of the visualization and make some sense out of it?
code here: